content: /*
   * Copyright 2017 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.reactive4javaflow.impl.operators;
  
  import hu.akarnokd.reactive4javaflow.*;
  import hu.akarnokd.reactive4javaflow.functionals.CheckedPredicate;
  import hu.akarnokd.reactive4javaflow.fused.ConditionalSubscriber;
  
  import java.util.concurrent.Flow;
  
  /**
   * Filters each 'rail' of the source ParallelFolyam with a predicate function.
   *
   * @param <T> the input value type
   */
  public final class ParallelFilter<T> extends ParallelFolyam<T> {
  
      final ParallelFolyam<T> source;
  
      final CheckedPredicate<? super T> predicate;
  
      public ParallelFilter(ParallelFolyam<T> source, CheckedPredicate<? super T> predicate) {
          this.source = source;
          this.predicate = predicate;
      }
  
      @Override
      public void subscribeActual(FolyamSubscriber<? super T>[] subscribers) {
  
          int n = subscribers.length;
          @SuppressWarnings("unchecked")
          FolyamSubscriber<? super T>[] parents = new FolyamSubscriber[n];
  
          for (int i = 0; i < n; i++) {
              FolyamSubscriber<? super T> a = subscribers[i];
              if (a instanceof ConditionalSubscriber) {
                  parents[i] = new ParallelFilterConditionalSubscriber<>((ConditionalSubscriber<? super T>) a, predicate);
              } else {
                  parents[i] = new ParallelFilterSubscriber<>(a, predicate);
              }
          }
  
          source.subscribe(parents);
      }
  
      @Override
      public int parallelism() {
          return source.parallelism();
      }
  
      abstract static class BaseFilterSubscriber<T> implements ConditionalSubscriber<T>, Flow.Subscription {
          final CheckedPredicate<? super T> predicate;
  
          Flow.Subscription s;
  
          boolean done;
  
          BaseFilterSubscriber(CheckedPredicate<? super T> predicate) {
              this.predicate = predicate;
          }
  
          @Override
          public final void request(long n) {
              s.request(n);
          }
  
          @Override
          public final void cancel() {
              s.cancel();
          }
  
          @Override
          public final void onNext(T t) {
              if (!tryOnNext(t) && !done) {
                  s.request(1);
              }
          }
      }
  
      static final class ParallelFilterSubscriber<T> extends BaseFilterSubscriber<T> {
  
          final FolyamSubscriber<? super T> actual;
  
          ParallelFilterSubscriber(FolyamSubscriber<? super T> actual, CheckedPredicate<? super T> predicate) {
              super(predicate);
              this.actual = actual;
          }
  
          @Override
          public void onSubscribe(Flow.Subscription s) {
              this.s = s;
  
              actual.onSubscribe(this);
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (!done) {
                  boolean b;
  
                  try {
                      b = predicate.test(t);
                  } catch (Throwable ex) {
                      FolyamPlugins.handleFatal(ex);
                      cancel();
                      onError(ex);
                      return false;
                  }
  
                  if (b) {
                      actual.onNext(t);
                      return true;
                  }
              }
              return false;
          }
  
          @Override
          public void onError(Throwable t) {
              if (done) {
                  FolyamPlugins.onError(t);
                  return;
              }
              done = true;
              actual.onError(t);
          }
  
          @Override
          public void onComplete() {
              if (!done) {
                  done = true;
                  actual.onComplete();
              }
          }
      }
  
      static final class ParallelFilterConditionalSubscriber<T> extends BaseFilterSubscriber<T> {
  
          final ConditionalSubscriber<? super T> actual;
  
          ParallelFilterConditionalSubscriber(ConditionalSubscriber<? super T> actual, CheckedPredicate<? super T> predicate) {
              super(predicate);
              this.actual = actual;
          }
  
          @Override
          public void onSubscribe(Flow.Subscription s) {
              this.s = s;
  
              actual.onSubscribe(this);
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (!done) {
                  boolean b;
  
                  try {
                      b = predicate.test(t);
                  } catch (Throwable ex) {
                      FolyamPlugins.handleFatal(ex);
                      cancel();
                      onError(ex);
                      return false;
                  }
  
                  if (b) {
                      return actual.tryOnNext(t);
                  }
              }
              return false;
          }
  
          @Override
          public void onError(Throwable t) {
              if (done) {
                  FolyamPlugins.onError(t);
                  return;
              }
              done = true;
              actual.onError(t);
          }
  
          @Override
          public void onComplete() {
              if (!done) {
                  done = true;
                  actual.onComplete();
              }
          }
      }}
  